WO2018158103A1

WO2018158103A1 - Security system

Info

Publication number: WO2018158103A1
Application number: PCT/EP2018/054072
Authority: WO
Inventors: Ashish Vijay Pandharipande; Hugo Jose KRAJNC; Remco MAGIELSE
Original assignee: Philips Lighting Holding B.V.
Priority date: 2017-03-02
Filing date: 2018-02-20
Publication date: 2018-09-07

Abstract

A security system has an alert function for a monitored area which, when active, responds to occupancy indicators for the monitored area by triggering intruder alerts. An initial occupancy indicator for the monitored area is received when the alert function for the monitored area is inactive. In response, illumination apparatus of the security system changes at least one characteristic of light in the monitored area, without triggering any intruder alert, and the alert function is activated for the monitored area. If a subsequent occupancy indicator for the monitored area is received from light sensing apparatus of the security system when the light in the monitored area is exhibiting the changed at least one characteristic, the active alert function responds by triggering an intruder alert. If no subsequent occupancy indicator is received for the monitored area from the light sensing apparatus, the change is reversed and the alert function is deactivated.

Description

SECURITY SYSTEM

TECHNICAL FIELD

The present invention relates to a security system for detecting intruders.

BACKGROUND

There is a growing need for security at homes. Camera sensors may be used for analyzing occupancy, particularly in surveillance applications. Recent advances in connected technology have made camera-based home security systems a more viable and affordable option, and they have become more prevalent as a result.

US9064394B1 discloses a monitoring system for e.g. visual surveillance, which can control operation of a lighting system to, for example, illuminate an area to provide a better image of an area captured by a camera.

SUMMARY

Existing security solutions use security cameras that come in two cost categories: cameras that provide good performance in different illumination conditions (e.g. low light levels at night, such cameras with infra-red sensing capabilities) but have an often prohibitively high cost, and cameras that are low cost but have a poor detection performance, leading to false alarms and missed detection in low-light conditions in particular.

A first aspect of the present invention is directed to a method of a security system detecting intruders, wherein the security system has an alert function for a monitored area which, when active, responds to occupancy indicators for the monitored area by triggering intruder alerts, the method comprising steps of: receiving an initial occupancy indicator for the monitored area when the alert function for the monitored area is inactive; and in response to the initial occupancy indicator: causing illumination apparatus of the security system to change at least one characteristic of light in the monitored area, without triggering any intruder alert, and activating the alert function for the monitored area, whereby if a subsequent occupancy indicator for the monitored area is received from light sensing apparatus of the security system when the light in the monitored area is exhibiting the changed at least one characteristic, the active alert function responds by triggering an intruder alert, wherein if no subsequent occupancy indicator is received for the monitored area from the light sensing apparatus, the change is reversed and the alert function is deactivated.

The at least one characteristic of light in the monitored area may comprise: intensity of light in the monitored area, color of light in the monitored area, and/or a dynamic characteristic of light in the monitored area.

For example, the intensity of light in the monitored area may be increased in response to the initial occupancy indicator and reduced if no subsequent occupancy indicator is received. That is, the light intensity level is increased to validate the initial occupancy indicator before any intruder alert is triggered (i.e. the presence of the subsequent occupancy indicator from the light sensing apparatus at the higher light intensity level means the initial occupancy indicator is valid, and the absence of any such occupancy indicator at the higher intently level means it is invalid). Advantageously, relatively basic, low-cost light sensing apparatus, such as low-cost cameras can be used; this does not increase the risk of false- alarms in poor illumination conditions because the intruder alert is only triggered if and when the intensity of light in the monitored area has been increased to a level sufficient for the light sensing apparatus to provide reliable occupancy detection.

However it is noted that the invention is not limited to increasing the light level (intensity) to lower the false positive triggers of an alarm system. For example, if the initial occupancy trigger comes in when the light level is too high (e.g. high enough to cause saturation at the light sensing apparatus) or the light output is too dynamic, the change can be reducing the light level or stopping a dynamic effect (or making it less dynamic).

Preferred embodiments of the present invention can be implemented using an interactive low-cost security camera network and a (connected) lamp network to improve security alarming in a home environment. Connected lighting is becoming increasingly prevalent in homes, and a connected lighting system provides a suitable and convenient operating environment for implementing embodiments of the invention.

The light sensing apparatus may comprise image capture apparatus, from which at least the subsequent occupancy indicator is received.

The method may comprise a step of transmitting image data to a user device, in response to the subsequent occupancy indicator, the image data being captured by the image capture apparatus from the monitored area when the light in the monitored area is exhibiting the changed at least one characteristic. The initial occupancy indicator may be received from the light sensing apparatus. However it could also be received from a non-light sensing device, such as a passive infrared sensor, ultrasonic sensor etc.

The subsequent occupancy indicator may correspond to a detectable face in the image data captured by the image capture apparatus, wherein the intruder alert is triggered in response to a facial recognition function classifying the face as unknown.

The method may comprise a step of measuring the at least one characteristic of the light in the monitored area, the alert function being activated in response to detecting said change in the measured characteristic.

Alternatively, the method may comprise a step of receiving from the illumination apparatus a confirmation signal, other than emitted light, confirming the change in the at least one characteristic of the light, the alert function being activated in response to the confirmation signal.

The light sensing apparatus may be activated to capture the subsequent occupancy indicator in response to the change in the at least one characteristic of light in the monitored area.

The light sensing apparatus may be periodically activated to capture the initial occupancy indicator.

The intruder alert may comprise an audible and/or visual alarm generated by alert apparatus of the security system and/or an alert outputted at a user device.

The at least one characteristic of light in the monitored area may be changed gradually from an initial value to a new value. For example, the intensity of light may be increased/decreased gradually from an initial level to a new level.

Alternatively, the increase may be sudden enough to be noticeable, e.g.

instantaneous. Here, a benefit is that, in addition to providing an improved detection, the change can also have a shocking/surprising effect for the intruder. This can cause him to exhibit sharper, more sudden, or larger motions, which are also easier to pick up by a camera (or other light sensing apparatus).

The initial occupancy indicator may be received when the light in the monitored area does not meet at least one illumination criterion, and the at least one characteristic of the light in the monitored area may be changed in response to the initial occupancy indicator so as to meet the at least one illumination criterion.

The alert function is activated whenever the at least one illumination criterion is met (e.g. which can mean that changes in an ambient light level in the monitored area or changes in the light output of the illumination apparats caused by some other means, such as a schedule, can also cause activation of the alert function), such that an occupancy indicator received from the lighting sensing apparatus when the at least one illumination criterion is met causes the active alert function to trigger an intruder alert without changing a light output of the light sensing apparatus.

For example, in the intensity scenario, an intruder alert may be triggered by an occupancy alert without changing the light level output if the system determines that the current light level is appropriate (e.g. over 50% or over a predetermined lux value).

A second aspect of the present invention is directed to a computer program product comprising code stored on a computer readable storage medium and configured when executed in a security system to implement the method of the first aspect or any embodiment thereof.

A third aspect of the present invention is directed to a controller for a security system, the controller having an alert function for a monitored area which, when active, responds to occupancy indicators for the monitored area by triggering intruder alerts, the controller comprising: a communication interface for communicating with illumination apparatus of the security system for emitting light into the monitored area; an input configured to receive information about the monitored area from light sensing apparatus of the security system; a lighting control component configured, in response to an initial occupancy indicator for the monitored area received when the alert function for the monitored area is inactive, to cause the illumination apparatus to change at least one characteristic of light in the monitored area, without any intruder alert being triggered; and an alert control component configured to activate the alert function for the monitored area in response to the initial occupancy indicator, whereby if a subsequent occupancy indicator for the monitored area is received from light sensing apparatus of the security system when the light in the monitored area is exhibiting the changed at least one characteristic, the active alert function responds by triggering an intruder alert, wherein if no subsequent occupancy indicator is received for the monitored area from the light sensing apparatus, the lighting control component is configured to reverse the change and the alert control component is configured to deactivate the alert function.

In embodiments, the controller may comprise an association component configured to associate at least one light sensing device of the light sensing apparatus with at least one illumination device of the illumination apparatus, wherein the lighting controller may be configured to identify that illumination device as associated with that light sensing device in response to the initial occupancy indicator, which is received from that light sensing device, and cause that illumination device to increase the intensity of light in the monitored area in response.

The association component may be configured to automatically associate the at least one light sensing device with the at least one illumination device in response to that light sensing device sensing a change in the light emitted by that illumination device.

Multiple illumination devices of the illumination apparatus may be associated with the light sensing device, and the lighting control component is configured to activate one or more, but not all, of those illumination devices in response to the initial occupancy indicator.

The association component may be configured to create weighted associations between the illumination devices and the light sensing device based on relative intensity changes sensed by those illumination devices in response to a change in an output intensity of the light sensing device.

The controller of the security system may comprise a detection component configured to detect at least the subsequent occupancy indicator in sensor data received from the light sensing apparatus (i.e. detection at the controller). Alternatively, the light sensing apparatus may be configured to capture sensor data to detect conditions of occupancy therein, wherein at least the subsequent occupancy indicator conveys a condition of occupancy detected by the light sensing apparatus (i.e. detection at the lighting apparatus).

Another aspect of the present invention is directed to method of a security system detecting intruders, wherein the security system has an alert function for a monitored area which, when active, responds to occupancy indicators for the monitored area by triggering intruder alerts, the method comprising steps of: receiving an initial occupancy indicator for the monitored area when the alert function for the monitored area is inactive; and in response to the initial occupancy indicator: causing illumination apparatus of the security system to increase an intensity of light in the monitored area, without triggering any intruder alert, and activating the alert function for the monitored area, whereby if a subsequent occupancy indicator for the monitored area is received from light sensing apparatus of the security system at the increased intensity, the active alert function responds by triggering an intruder alert, wherein if no subsequent occupancy indicator is received for the monitored area from the light sensing apparatus, the intensity of light in the monitored area is reduced and the alert function is deactivated. BRIEF DESCRIPTION OF FIGURES

For a better understanding of the present invention, and to show how embodiments of the same may be carried into effect, reference is made to the following figures in which:

Fig. 1 shows a schematic block diagram of a security system;

Fig. 2 shows a flowchart for a method of detecting intruders;

Fig. 3 illustrates a first example signaling flow in a security system;

Fig. 4 illustrates a second example signaling flow in a security system; and

Fig. 5 shows a functional block diagram representing part of the functionality of a security system controller in certain embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Providing mechanisms for security at homes in particular is becoming increasingly important. However, as noted, existing surveillance camera solutions are either expensive or have poor performance in low-light conditions.

To solve this problem, the security system of the described embodiments uses a combination of connected lamps and low-cost camera sensors to provide a reliable security alarming solution. The solution is based on a multi-stage detection and actuation of the lamps and camera sensor system.

With reference to figure 1, the described security system 100 is a connected lighting system having at least selectable security mode (and in some cases multiple security modes - see below). The connected lighting system 100 comprises illumination apparatus 108 in the form of one or more (preferably multiple) illumination devices (luminaires), which are connected lamps; a controller 102; and light sensing apparatus 110 for sensing light, in the form of one or more light sensing devices. In some embodiments, the system 100 also comprises alert apparatus 1 14, comprising at least one alert device, i.e. a device that can generate an audible and/or visual alarm (not necessarily co-located), preferably a loud burglar alarm-style alert and/or flashing lights within a user's home. The alert need not necessarily be displayed or otherwise executed in the same environment as the controller 102 or the lighting system 100. For example, the controller 102 can instigate a digital communication, which triggers the alert in some other environment, such as a third -party home security system in communication with the lighting system 100. For example, an intruder alert can be triggered at an external system by "passing on" a detected occupancy indicator to an external (e.g. third-party) system. That is, by conveying the receipt of an occupancy indicator to the external system.

Preferably, the light sensing apparatus 1 10 comprises image capture apparatus. That is, preferably at least one of the light sensing devices is an image capture device (camera/camera sensor).

Connected lighting refers to a class of lighting system in which the luminaires can be controlled based on the communication of data between the lights and a controlling device (such as a smartphone, tablet, smart-switch etc.) using network technology, according to a network communications protocol or combination of such protocols, such as ZigBee, Bluetooth, TCP/IP (e.g. over Wi-Fi, Ethernet or a combination of both), Z-Wave, Thread etc.

A connected lamp means an illumination device comprising a network interface so that it can be controlled based on network communication technology, such as but not limited to one of those mentioned in the preceding paragraph or any combination thereof. Multiple connected lamps connected to the controller 102 form a lighting network controlled by the controller 102. The camera sensors can also be incorporated in the lighting network to allow them to communicate with the controller 102 via the lighting network. Each of the lamps/cameras can connect to the controller 102 directly, or alternatively at least one of the lamps and/or cameras can connect to it indirectly via one or more other lamps/cameras of the lighting network, which relay data between that lamp and the controller: a so-called mesh topology. For example, ZigBee networks can operate with a mesh topology. The cameras could also be connected directly to the lamps, e.g. a Wi-Fi/Bluetooth lamp and a Wi- Fi/Bluetooth camera. In this case the controller 102 can be part of the lamp or camera (or part can be implemented at the lamp and part at the camera).

The lighting network may comprise a bridge (also called a gateway), which connects the lighting network to another network 116 operating according to a different (set of) protocol(s), such as TCP/IP. For example, a local area network and/or the public Internet. The bridge allows a device connected to the other network 116, such as a user device 118 (e.g. smartphone, tablet or other smart device, personal computer, wearable device, or other general purpose computing device, a smart home hub or other smart home device etc.) to communicate with the lighting network, and in particular allows such devices to be used to control the lamps. The bridge can be part of one of the lamps themselves, or it may be a separate device in the lighting network. However, the described techniques can be implemented without a bridge, for example the lamps may connect to the other network 1 16 directly, e.g. via Wi-Fi, so that they can be controlled from a device, such as the user device 1 18, connected to the same network. Alternatively, a device, such as the user device 1 18, may control the lamps directly, e.g. using Bluetooth, in which case that device need not be connected to the other network 1 16 in order to control the lamps.

The controller 102 can be implemented in various different ways. For example, the controller 102 can be implemented at the bridge of the lighting network, when present; as part of the lighting apparatus 108 itself, i.e. at one (or more) of the lamps; as part of the image capture apparatus 1 10 itself, i.e. at one (or more) of the image capture sensors; at the user device 1 18; as part of the alert apparatus 114 itself; as part of a (third-party) smart home device; or remotely at a device(s) on the public Internet, such as a server(s) (e.g. portal; not shown). Alternatively, the controller can be a distributed controller, for example implemented at two or more such devices, for example in part at the bridge and in part at the image capture device(s) and/or the lamp(s) etc. That is, the controller 102 may be distributed such that different parts of its functionality are implemented at different places within the system, locally and/or remotely.

The controller 102 is shown to comprise a lighting control component 104 and an alert control component 106. The controller 102 is also shown to have an alert function 107, which can be selectively activated and deactivated by the alert control component 106, as explained below.

For now, suffice it to say that the alert function 107, when active for a particular area 109 (and only when active for that area), triggers intruder alerts, from the alarm apparatus 114 and/or the user device 1 18, in response to occupancy indicators received for that area 109 for which it is active. The lighting control component 108 is able to control the lighting control apparatus 108, in order to adjust the intensity of light emitted by it. The alert control component 106 activates and deactivates the alert function 107 depending on the light level in the area 109, in the manner described below. This means there may be times when the lighting system is operating in the security mode and the alert function 107 is in active for one or more such areas, and that an occupancy indicator detected in that area will not trigger intruder alerts in that event; rather, the light level is increased in the area in question to first validate the occupancy indicator using the light sensing apparatus 110, and an intruder alert is only triggered by the now-active alert function 107 if a subsequent occupancy indicator received for that area 109 at the increased light intensity from the light sensing apparatus 110 confirms that the initial occupancy indicator was valid.

The controller 102 is also shown to comprise a communication interface 103 via which the controller 102 can communicate with other components of the system 100, and in particular the illumination apparatus 108 and image capture apparatus 110. The controller 102 can also communicate with at least one of the user device 1 18 and the alert apparatus 1 14, in order to trigger an intruder alert for alerting the user of the security system when the occupancy of the area 109 has been validated (indicating a likely intruder). For a security system with multiple users, an intruder alert can be triggered at each of their devices.

The communication interface 103 can for example comprise at least one network interface for communicating with an external lamp/camera device/alert device/user device based on a particular network technology or technologies, and/or an internal interface for controlling a lamp/camera device/alert device/user device in which (part of) the controller 102 is integrated etc.

The operation of the connected lighting system 100 in the security mode will now be described with reference to figure 2, which is a flowchart for a method of detecting intruders that is implemented by the controller 102. By way of example, the method is described in the context of a camera of the image capture apparatus 110 and one or more lamps of the illumination apparatus 108 in the vicinity of and associated with the camera. The camera has a field-of-view (FoV), from which it can capture image data. The field-of-view is shown to define the monitored area 109 of figure 1, in which visible events are detectable to the camera, and which is monitored for intruders using the camera.

As will be apparent in view of the following, the techniques can be extended readily to include the use of multiple cameras monitoring respective areas (at least some of which may overlap). Each camera sensor may be monitoring a specified area determined by its FoV, for instance facing different potential entry points for an intruder (doors/windows in particular). According, all description below pertaining to the camera applies to each camera in this context.

The camera sensor can communicate, potentially bi-directionally (either directly or via intermediate relay devices), with the controller 102, e.g. the lamps and/or the bridge depending on where the controller 102 is implemented.

The method begins at step S202 when an overall light intensity within the camera's field-of-view is at an initial level. Preferably, the associated lamps are off (i.e. not emitting light) at this point or at least emitting light at only a low intensity level, so as not to waste energy illuminating an unoccupied environment. However, this means that that the only contribution to the overall light intensity within the field-of-view is ambient light (e.g. natural light), which may be low at night or if the environment is receiving no or little ambient light for some other reasons (the blinds/curtains may be drawn, the environment may be a windowless room etc.).

The alert control component 106 is configured to deactivate the alert function 107 based on information 105 relating to the intensity level in the monitored area 109. For example, the alert function may be deactivated whenever the associated lamps are off, or more generally when their (combined) illumination output is below a detection threshold - ignoring any contribution from ambient light in the area 109. This information simply may be known to the controller 102, because the state of the lamps has been set by the lighting control component 104 (which does not require an extra signaling). Alternatively the status of the lamps can be conveyed explicitly from the lamps to the controller. Such explicitly conveyed information is labeled 105E in figure 1, and is conveyed using some means other than (visible) light, for example as RF (radio frequency) signals, or current/voltage modulations etc. However, preferably, the light intensity information 105 is determined for the area 109 using the light sensing apparatus 109 itself, i.e. information from the camera itself and/or another light sensing device(s) in the vicinity of the camera, such as a photo sensor, to take into account any ambient light in the monitored area 109. For example, the alert function 107 may be deactivated whenever a light intensity measured in the area 109 using the light sensing apparatus 110 is below a detection threshold.

More generally, the alert function 107 can be activated and deactivated using the light intensity information 105 for the monitored area 109 based on one or more illumination criteria, as in the example below. Note however that this example is not exhaustive and that other examples are given later.

For the purposes of explanation, it is assumed that at step S202, the security mode is enabled, these illumination criteria are not met and that the alert function 107 is inactive as a consequence.

At step S204, the camera sensor captures a first (initial) occupancy trigger that is received by the controller 102, which in this example is caused by activity of an intruder 112 in the monitored area 102. However, because the illumination criteria for the monitored area 109 are not met, this cannot be relied upon for the controller 102 to conclude that an intruder is present; such an occupancy trigger may also be caused by other factors, so it would be premature to alert the user of the security system at this point. Because the alert function 107 is inactive, no intruder alert is triggered in response to the initial occupancy trigger. Rather, the controller 102 responds (S206) by controlling one or more lamps of the illumination apparatus 108, which are associated with and in the vicinity of the camera, to create an illumination change in the field-of-view of the camera sensor that is above a certain threshold value. That is, to increase the overall intensity of light in the monitored area 109, from the initial level to a new level. An area 109L is shown in figure 1, which (partially) overlaps with the monitored area 109 and approximately corresponds to an illumination footprint cast by a lamp of the illumination apparatus 108 collocated with the camera (however this is purely for the purposes of illustration). Depending on the implementation, this increase is such that the intensity of light emitted by the lamps (ignoring any ambient light) is above the detection threshold, or such that the overall intensity (including ambient light) in the area 109 is above the detection threshold. For the latter, it is noted, for completeness, that an increase in the monitored area 109 caused by an increase in ambient light will also cause the alert function 107 to be activated if it takes the overall intensity level in the monitored area 109 above the detection threshold.

For example, the first occupancy trigger may actuate the lamps to set them to a maximum intensity level or some other pre-set level.

If a single lamp cannot provide sufficient light in the desired area, other nearby lights might also switch on to reach the desired level. In a case where the lights are not specifically linked to a location, as a fallback, the controller 102 can simply active all of the lamps it has access to.

The increase may be essentially instantaneous, or alternatively, the lamps may be dimmed from a low dimming level to a higher dimming level in a difficult to perceive manner so that the intruder 1 12 does not get alerted. That is, the intensity of light in the monitored area 109 may be increased gradually, so as not to alert the intruder 1 12; for example from the initial level to the new (final) level, over an interval of five seconds or more. In the example of a camera sensor "gradually" means the change is sufficiently slow that it does not result in changes across adjacent captured image frames.

In any event, at step S208, the alert controller 106 activates the alert function 107 in response to the initial occupancy indicator and the resulting increase in the light intensity in the area 109. This can simply be a case of the alert controller 106 activating the alert function 107 as the lighting controller 104 instructs the lamps (i.e. the controller 102 simply assumes the lamps will respond as instructed, without verifying this). Alternatively, it can use the information 105E signaled explicitly from the lamps about their new illumination status, which constitutes a confirmation signal in this context (i.e. an explicit signal, other than light emitted by the illumination apparatus 108, confirming that the increase has taken place as instructed), and/or the increase in the illumination can be actively detected using the light sensing apparatus 110, for example the camera itself or another light sensing device of the light sensing apparatus 108 in the camera's vicinity.

At step S210, the method branches depending on whether or not a second

(subsequent) occupancy indicator, verifying the initial occupancy indicator, is received from the camera at the increased in intensity level. At this point, the alert function 107 is active, so if a second occupancy indicator is received from the camera, the active alert function 107 triggers (S214) an intruder alert in the manner described above.

However, if no subsequent occupancy indicator is received at the increased illumination level within a time limit (e.g. within a few seconds or minutes of the initial occupancy indicator), then at step S212 the alert function 107 is deactivated and the associated lamps are controlled to return to the initial intensity level. Preferably, the associated lamps are deactivated at this point to conserve energy. The method then returns to step S202, where monitoring resumes as before with the alert function 107 inactive, and proceeds in the same way if and when another occupancy indicator is detected with the alert function 107 inactive.

To avoid having to capture a continuous stream of image data, the camera is preferably only activated periodically when the alert function 107 is inactive, to capture individual images (or short sequences of video data).

In this case, the camera may also be activated to capture a new image, or to begin capturing a continuous video stream, when the alert function 107 is activated, i.e. in response to the increase in the light intensity level in the area 109, to capture the second occupancy indicator.

For example, an actuation signal may sent from the bridge (or directly from the lamps) to the camera sensor to generate a second detection, from which it is determined whether a second occupancy indicator is present or not. That is, so the camera sensor is activated to perform a further detection that is used for security alarming, by the now-active alert function 107, if presence is still indicated in the area 109.

Image data may be received at the controller 102 from the camera and at least the subsequent occupancy indicator may be detected in the received sensor data by the controller 102. That is, the subsequent occupancy indicator may be a characteristic of the received image data that a detection component of the controller (not shown) detects in the received image data. Alternatively, the subsequent occupancy indicator can be detected at the camera itself and signaled explicitly from the light sensing device to the controller, for example as a binary occupancy/no occupancy value in the simplest case. In that case, persistence of the occupancy value once the intensity of light in the monitored area has been increased triggers the intruder alert, the subsequent occupancy indicator being occupancy value that persists following the increase in the light intently level in that event.

That is, the camera sensor output may be a detection (e.g. a binary occupancy value), image(s) or an illuminance change value, or any combination thereof.

Optionally, as well as triggering the intruder alert, the controller 102 may also send the image data captured by the camera to the user device 118 (or cause it to be sent to the user device 1 18 directly from the camera), for example a current image or a live video stream of the area 109 so that the user can see the intruder 112 in the area 109 at the now- increased intensity. That is, the controller 102 may generate a security alarm to a (possibly remote) smartphone, optionally along with images. The user can be provided, via a user interface of the user device 118, with an option to, say, activate an (additional) alarm if there is a genuine intruder, or deactivate an alarm for a false-trigger.

It is noted that the above described techniques, whilst described in the context of the camera, are not limited in this respect. As will be appreciated, they can be applied equally to other forms of light sensing device, such as photo sensors.

It is also important to note that the initial occupancy trigger of step S204 need not come from a light sensing device at all, and could come from another form of sensing device, such as a passive infrared sensor (PIR) or other (preferably low cost) non-light-based sensor. In that event, the non-light-based sensor triggers the activation of the lamps upon sensing occupancy, allowing the light sensing apparatus 1 10, such as a camera or cameras thereof, to be used to verify the result (now that there is sufficient light for it to do so reliably) before triggering the intruder alert if step S214. This additional sensing device does not necessarily need to share the same low-lighting conditions-low performance issues as the camera, but it might not be able to provide as accurate information as a camera, or it may run into other pitfalls for which a dual sensor approach is necessary which mean it is beneficial to validate the initial trigger using a camera in appropriate lighting conditions.

It may also be possible to use the camera to implement more advanced functions: for example a PIR sensor could detect a motion exhibited by a person and a camera vision techniques may be used detect whether it is the person is known, for example using facial recognition, and trigger an intruder alert if the person is unknown. Similarly, the camera itself could detect the motion at a light level insufficient for facial recognition, and the light level is increased to make facial detection possible.

Note that, whilst in the above, the alert function 107 is activated in dependence a detection threshold, in some contexts it may be preferable to increase light levels after a detection to corroborate the measurement regardless of whether the initial measurement was performed in a low intensity environment or not. For example, more generally, the alert function 107 may be inactive unless there is an optimal illumination state in the monitored area 109 (such that it inactive the majority of the time in practice). In this case, the initial occupancy indicator may be received with the alert function 107 inactive at a reasonably high but nonetheless suboptimal intensity level and cause the system to render the optimal illumination state and activate the alert function 107; a further occupancy alert in the optimal illumination state then triggers the now-active alert function 107 to trigger an alert.

Referring to figure 5, in order to associate the (or each) camera with one or more lamps in its vicinity, the controller preferably comprises an association component 304, which creates associations 307 between the camera and the one or more lamps in its vicinity. These associations 307 are electronically recorded in a memory accessible to the controller 102. Preferably, they are created automatically, in the manner described below. From the recorded associations 307, the lighting control component 104 can determine which lamp or lamps of the illumination apparatus 108 to activate in response to an initial occupancy indicator from a particular camera of the image capture apparatus 1 10.

In an initial configuration phase the association component 304 associates each camera sensor with one or more lamps that result in an illumination change in the FoV of that camera sensor that is above a certain threshold value. In the following examples, at least the association component 304 of the controller 102 is implemented at the bridge of the lighting network in, but it can be implemented elsewhere in the system. The same techniques can also be applied to other types of light sensing device.

These associations can be created in many ways. For example, a lamp actuation based on user interaction, as well as lamp IDs, along with illumination changes in different camera sensors can be captured by at the bridge over time, based on which lamps and sensors are associated. For instance, when a user switches on lamp 1, the bridge data can be record as illustrated in table 1 below: TABLE 1 :

As can be seen from table 1 , actuation of lamp ID 1 results in an illumination increase in camera sensor IDl (at t2-t4) and hence this lamp and camera sensor are associated with each other. Hysteresis or threshold values can be used to ensure that the association is robust against ambient/digital noise and/or other external phenomenon (car passing at night and shining lights at window, cloud blocking sun, etc.)

The bridge can for example actuate each lamp at a time and the illumination changes in different camera sensors is captured at the bridge over time, based on which lamps and sensors are associated.

Alternatively, the lamps may transmit IDs (via visible light communication, for instance) that are detectable by the camera sensors. If a lamp has IDl and is detected only by camera sensor 1, then these are associated with each other.

The associations can be more complex than these simple examples. For example, a lamp may contribute to an illumination change detectable by more than one camera sensor and, as such, may be associated with multiple cameras.

The associations may also be weighted associations, which take into account the extent to which illumination changes are visible to different sensors. For example if Camera A senses an increase of 2001x, Camera B senses an increase of 601x, and Camera C senses an increase of lOlx, it may be assumed that the lamp is most impactful to Camera A, has limited impact on Camera B, but has no impact on Camera B (as the lOlx increase can be considered noise or irrelevant).

The linking of weighting factors to cameras can be useful in identifying how to optimally select the lights to increase brightness With reference to figure 3, a preferred use case will now be described. The system 100 is set in a security alert mode, for instance when all users are away from home. When the intruder 1 12 attempts a break- in, say at night time, resulting in a first detected motion, the following signaling steps occur, corresponding to steps 1-5 in figure 3 respectively:

Step 1 : A camera sensor generates a first sensor trigger to one or more associated lamps that result in an illumination change in the field-of-view of the camera sensor that is above a certain threshold value.

Step 2: The trigger actuates the associated lamps to turn on or to a pre-set dimming level (the actuation may be performed directly from the camera sensor to the lamp, if there is direct communication via a common protocol, or via the bridge).

In some embodiments, the lamps are dimmed from a low dimming level to a higher dimming level in a difficult to perceive manner (so that an intruder does not get alerted).

Moreover, when multiple lamps may be associated with a camera sensor, the controller 102 may actuate a lamp whose illumination change is least noticeable to an intruder. There may also be multiple lamps with different colors/color temperatures already on. In this case the lamp properties can be tuned so as to improve detection subsequent to actuation of the camera sensor by the lamps.

Step 3: Optionally, an actuation signal is sent from the bridge (or directly from the lamps) to the camera sensor to generate a second detection (in general, multiple detections and actuations may be used to generate a sequence of images, based on which alarming is done and made more reliable); alternatively, the camera may detect the change autonomously.

Step 4: The camera sensor provides a detection that is used for security alarming;

Step 5: The bridge (or the camera sensor) generates a security alarm to a (possibly remote) smartphone, optionally along with images assuming the presence of the intruder is verified by the system (if a second scan yields no movement the system will not trigger). As noted, it is also possible for a third-party device to act as the controller 102 (such as a separate smart home hub or other smart home device). In this case, the third-party device may receive and send triggers to both camera and the bridge to carry out these functions.

With reference to figure 4, in a variant of this use case, in response to a first trigger from a camera sensor, the bridge actuates all lamps (1A, IB), rather than actuating the lamps associated to the camera sensor in the previous example. In that case, there is no need for the association component 304.

This has the advantage of avoiding an additional cycle if intruder presence is detected at a second camera sensor (i.e. if there is a security concern that there might be one or more intruders, surveillance becomes active over the whole home, and not in a specific area). It is also beneficial if, between detections, the intruder moves to a different room or into a different camera's FoV.

This described system differs from existing occupancy detection and security systems in a number of respects. Firstly, existing systems are limited to actuating luminaires; whereas in the preferred implementations of the present system there is further signaling from the luminaires back to the occupancy sensor (either explicit, or through detection of their emitted light), to then activate the occupancy sensor for security purposes, i.e. activate the alert function 107. That is, in existing systems, occupancy sensors are simply used to actuate the luminaires, and not the other way around. Secondly, the detection mechanism described herein, where the detection is dependent on a lighting action, is also different from existing systems.

As noted, it may be possible for the system to have several security modes, where a variable could be for example what level of reliability is desired in the detection and/or alert. E.g. if this is set at night while people are sleeping, it might be desirable to make a large increase in brightness to both scare an intruder and make sure there's absolutely no chances of a missed detection to minimize the chances of the intruder getting deeper into the house (first security mode); however, if set while on holidays, then it might be beneficial to effect minor increases in brightness to avoid alerting the burglars while at the same time giving time for the alert to result in an action,, e.g. police arriving to house (second security mode)

It is important to note that lighting control component 104, alert control component 106, association component 304, and any other described components of the controller 102, as well as the alert function 107, are functional components of the controller 102, representing different parts of the controller's functionality, and are not necessarily separate physical components. Preferably, the functionality of the controller 102 is implemented in software, i.e. by control code executed on a processor (e.g. CPU or CPUs) or processors of the controller 102, in which case the component 103, 106 and alert function 107 represent different parts of the functionality implemented by the control code when executed. In such implementations, the (or each) processor of the controller 102 is configured to fetch computer-readable instructions of the control code from memory and execute the fetched instructions to carry out the relevant part of the functionality. However, the possibility of implementing some or all of this functionality using dedicated hardware, such as an application-specific integrated circuit and/or programmable hardware (e.g. FPGA), is also not excluded.

It will be appreciated that the above embodiments have been described by way of example only. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A method for a security system (100) detecting intruders (1 12), wherein the security system has an alert function (107) for a monitored area (109) which, when active, responds to occupancy indicators for the monitored area by triggering intruder alerts, the method comprising the steps of:

receiving an initial occupancy indicator for the monitored area when the alert function for the monitored area is inactive and when the light in the monitored area does not meet at least one illumination criterion; and

in response to the initial occupancy indicator:

causing illumination apparatus (108) of the security system to change at least one characteristic of light in the monitored area so as to meet the at least one illumination criterion, without triggering any intruder alert, and

activating the alert function for the monitored area, whereby if a subsequent occupancy indicator for the monitored area is received from light sensing apparatus (1 10) of the security system when the light in the monitored area is exhibiting the changed at least one characteristic, the active alert function responds by triggering an intruder alert, wherein if no subsequent occupancy indicator is received for the monitored area from the light sensing apparatus, the change is reversed and the alert function is deactivated;

wherein the alert function for the monitored area is further activated whenever the at least one illumination criterion is met, such that an occupancy indicator received from the lighting sensing apparatus (1 10) when the at least one illumination criterion is met causes the active alert function to trigger an intruder alert without changing a light output.

2. A method according to claim 1, wherein the at least one characteristic of light in the monitored area comprises: intensity of light in the monitored area, color of light in the monitored area, and/or a dynamic characteristic of light in the monitored area.

3. A method according to claim 2, wherein the intensity of light in the monitored area is increased in response to the initial occupancy indicator and reduced if no subsequent occupancy indicator is received.

4. A method according to claim 1, 2 or 3, wherein the light sensing apparatus comprises image capture apparatus, from which at least the subsequent occupancy indicator is received.

5. A method according to claim 4, comprising a step of transmitting image data to a user device (1 18) in response to the subsequent occupancy indicator, the image data being captured by the image capture apparatus from the monitored area when the light in the monitored area is exhibiting the changed at least one characteristic.

6. A method according to any preceding claim, wherein the initial occupancy indicator is received from the light sensing apparatus.

7. A method according to any preceding claim, comprising:

a step of measuring the at least one characteristic of the light in the monitored area, the alert function being activated in response to detecting said change in the measured characteristic, or

a step of receiving from the illumination apparatus a confirmation signal (105E), other than emitted light, confirming the change in the at least one characteristic of the light, the alert function being activated in response to the confirmation signal.

8. A method according to any preceding claim, wherein the light sensing apparatus is activated to capture the subsequent occupancy indicator in response to the change in the at least one characteristic of light in the monitored area.

9. A method according to claims 6 and 8, wherein the light sensing apparatus is periodically activated to capture the initial occupancy indicator.

10. A method according to any preceding claim, wherein the at least one characteristic of light in the monitored area is changed gradually from an initial value to a new value.

1 1. A computer program product comprising code stored on a computer readable storage medium and configured when executed in a security system to implement the method of any preceding claim. 12. A controller for a security system (100), the controller having an alert function

(107) for a monitored area (109) which, when active, responds to occupancy indicators for the monitored area by triggering intruder alerts, the controller comprising:

a communication interface (103) arranged for communicating with illumination apparatus (108) of the security system for emitting light into the monitored area;

an input configured to receive information about the monitored area from light sensing apparatus (1 10) of the security system;

a lighting control component (104) configured, in response to an initial occupancy indicator for the monitored area received when the alert function for the monitored area is inactive and when the light in the monitored area does not meet at least one illumination criterion, to cause the illumination apparatus to change at least one characteristic of light in the monitored area so as to meet the at least one illumination criterion, without any intruder alert being triggered; and

an alert control component (106) configured to activate the alert function for the monitored area in response to the initial occupancy indicator, whereby if a subsequent occupancy indicator for the monitored area is received from light sensing apparatus of the security system when the light in the monitored area is exhibiting the changed at least one characteristic, the active alert function responds by triggering an intruder alert, wherein if no subsequent occupancy indicator is received for the monitored area from the light sensing apparatus, the lighting control component is configured to reverse the change and the alert control component is configured to deactivate the alert function;

wherein alert control component (106) is further configured to activate the alert function for the monitored area whenever the at least one illumination criterion is met, such that an occupancy indicator received from the lighting sensing apparatus (110) when the at least one illumination criterion is met causes the active alert function to trigger an intruder alert without changing a light output.

13. A controller according to claim 12, comprising an association component

(304) configured to automatically associate at least one light sensing device of the light sensing apparatus with at least one illumination device of the illumination apparatus in response to that light sensing device sensing a change in the light emitted by that illumination device;

wherein the lighting controller is configured to identify that illumination device as associated with that light sensing device in response to the initial occupancy indicator, which is received from that light sensing device, and cause that illumination device to change the at least one characteristic of light in the monitored area in response.